Direct acting variable valve lift apparatus

ABSTRACT

The present invention provides a variable valve lift apparatus including an outer body in which a hole is formed horizontally, and that moves upward/downward while slidingly contacting a high cam, an inner body that is inserted in the outer body, a hole is formed in steps such that the hole of the inner body is connected with the hole of the outer body, and moves upward/downward while slidingly contacting a low cam, a latching device that is inserted in the holes of the outer body and the inner body, and causes the movement of the outer body to be selectively dependent on the movement of the inner body, a plate that is located at a side of the latching device such that oil discharge from the outer body can be prevented, an upper seat that partially covers the inner body, and in which an oil passage is formed, and a lost motion spring that is located in the upper seat and provides the outer body with elastic force.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application Nos. 10-2010-0121619 and 10-2010-0121620 filed Dec. 1, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a variable valve lift apparatus. More particularly, the present invention relates to a variable valve lift apparatus in which a latching pin moves inside an outer body and an inner body, and the outer body and the inner body are formed in steps such that the latching pin can be blocked without additional devices, or such that the movement of the outer body is selectively dependent on the movement of the inner body, so valve lift is varied.

2. Description of Related Art

Generally, an internal combustion engine generates power by burning fuel and air input into a combustion chamber. Intake valves are operated by a camshaft, and air is input into the combustion chamber when the intake valves are open.

Also, exhaust valves are operated by a camshaft, and the air is exhausted from the combustion chamber when the exhaust valves are open.

Optimum operation of the intake valves/exhaust valves is changed according to engine speed.

That is, an appropriate lift or an appropriate opening/closing time is changed according to the engine speed.

In order to realize appropriate valve operation according to the engine speed, the cams driving the valves are multiply designed, and a variable valve lift (VVL) in which the valves can operate at different lifts according to the engine speed has been researched.

FIG. 8 is a cross-sectional view of a conventional variable valve lift apparatus, wherein if oil is supplied through an oil passage 51, a first pin 10 presses a second pin 20 and the second pin 20 pushes a third pin 30, so upward/downward movement of a side tappet 80 is dependent on movement of a center tappet 90.

At this time, the center tappet 90 slidingly contacts a high cam, and the side tappet 80 slidingly contacts a low cam.

Because the oil is not supplied in low lift mode, the side tappet 80 and the center tappet independently move upward/downward, and then the center tappet 80 fulfills the low lift mode while it performs lost motion by a lost motion spring 70.

However, because the oil is supplied in the high lift mode, the movements of the center tappet 90 and the side tappet 80 are dependent on each other by the first pin 10.

In this way, the valve is lifted as high as the size of the lobe on the high cam by the rotation of the high cam such that the high lift mode is fulfilled.

Then, since the oil must be discharged outside through the oil passage 51 to convert the high lift mode into the low lift mode, a stopper 50 must be formed at a side of the first pin 10 in order to prevent the first pin 10 from excessively moving and blocking the discharge of the oil.

However, the variable valve lift apparatus needs three latching pins 10, 20, and 30, and an additional stopper 50 is needed to prevent the movement of the latching pin such that the structure is complicated.

Undescribed references 40 and 60 designate a plate and a latching spring respectively.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF INVENTION

Various aspects of the present invention provide for a direct acting variable valve lift apparatus having advantages that movement of an inner body or an outer body can be dependent on movement of a latching pin by forming the inner body or the outer body in steps.

Various aspects of the present invention provide for a variable valve lift apparatus including an outer body in which a hole is formed horizontally, and that moves upward/downward while slidingly contacting a high cam, an inner body that is inserted in the outer body, a hole is formed in steps such that the hole of the inner body is connected with the hole of the outer body, and moves upward/downward while slidingly contacting a low cam, a latching device that is inserted in the holes of the outer body and the inner body, and causes the movement of the outer body to be selectively dependent on the movement of the inner body, a plate that is located at a side of the latching device such that oil discharge from the outer body can be prevented, an upper seat that partially covers the inner body, and in which an oil passage is formed, and a lost motion spring that is located in the upper seat and provides the outer body with elastic force.

The latching device according to the first and the various aspects of the present invention can include a plunger that moves from side to side by selective oil supply, a latching pin of which a side thereof contacts the plunger and the other side thereof is formed in steps such that the latching pin is blocked by the stepped holes of the outer body and the inner body, and a latching spring that covers the latching pin and provides the latching pin with elastic force while being supported by the supporting portion of the outer body.

The latching pin according to various aspects of the present invention can be formed with two steps, and the inner diameter of the outer body is formed in a smaller size than the diameter of the end in the other side of the latching pin such that a stepped jaw can be formed to prevent the latching pin from moving.

The latching pin according to various aspects of the present invention can be formed with three steps, the inner diameter of the inner body is formed in a smaller size than the diameter of the second protruded portion in the latching pin such that a stepped portion can be formed to prevent the latching pin from moving.

A protrusion according to various aspects of the present invention can be formed at a side of the plunger.

The oil passage formed in the upper seat according to various aspects of the present invention can be slanted, and can be connected with a latching device insertion hole formed in the outer body.

A shim contacting a valve according to the various aspects of the present invention can be formed at the bottom of the inner body.

Other aspects of the present invention provide for a variable valve lift apparatus including an outer body in which an oil chamber is formed horizontally and a protruded portion is formed inward and moves upward/downward while slidingly contacting a cam, an inner body that is inserted in the outer body, a latching pin hole is formed to be connected with the oil chamber of the outer body, and moves upward/downward while slidingly contacting a low cam, at least one latching device that moves through the latching pin hole and the oil chamber and causes the movement of the outer body to be selectively dependent on the movement of the inner body, a plate that is located at a side of the latching device such that discharge of oil from the outer body is prevented, an upper seat that partially covers the inner body and in which an oil passage is formed, and a lost motion spring that is located in the upper seat, and provides the outer body with elastic force.

The latching device according to various aspects of the present invention may include a latching pin of which a side thereof contacts oil and the other side thereof moves into the inner body by selective oil supply, and a latching spring that partially covers the latching pin and provides the latching pin with elastic force.

The latching device according to various aspects of the present invention may be respectively located at both ends of the latching pin hole of the inner body. An inner diameter of the other side in the latching pin according to the third exemplary embodiment of the present invention may be the same size as the diameter of the latching pin hole of the inner body.

The latching spring according to various aspects of the present invention may be located between the protruded portion of the outer body formed in a step, and the jaw of the latching pin. A protrusion according to the third exemplary embodiment of the present invention may be formed at a side of the latching pin. The oil passage formed in the upper seat according to the third exemplary embodiment of the present invention may be connected with an oil chamber formed in the outer body.

The outer body and the upper seat according to various aspects of the present invention may be integrally formed.

As described above, the latching pin may be formed with two or three steps, and the inner body or the outer body are formed corresponding to the latching pin such that the stepped structure can prevent the latching pin from moving, without additional devices, and the structure can be simplified. Further, oil supply can be fulfilled smoothly by a protrusion of the latching pin.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary variable valve lift apparatus according to the present invention.

FIG. 2 is a cross-sectional view of an exemplary variable valve lift apparatus according to the present invention.

FIG. 3 is a cross-sectional view and a perspective view of the combination an upper seat with an outer body according to various embodiments of the present invention.

FIG. 4 is a cross-sectional view of the variable valve lift apparatus combined with a cam of FIG. I.

FIG. 5 is a perspective view of an exemplary variable valve lift apparatus according to the present invention.

FIG. 6 is a cross-sectional view of the variable valve lift apparatus of FIG. 5.

FIG. 7 is a cross-sectional view of the variable valve lift apparatus combined with a cam of FIG. 5.

FIG. 8 is a cross-sectional view of the conventional variable valve

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

The present invention relates a direct acting variable valve lift apparatus, and FIG. 1 and FIG. 2 illustrate cross-sectional views of an exemplary variable valve lift apparatus according to various embodiments of the present invention.

A variable valve apparatus according to various embodiments of the present invention, as shown in FIG. 1 and FIG. 2, includes an outer body 100 into which a latching device insertion hole 120 and a latching pin insertion hole 160 are formed horizontally therein, and that moves upward/downward while slidingly contacting a high cam.

Also, the variable valve apparatus includes an inner body 200 that is inserted in the center of the outer body 100 in a length direction, a latching pin movement hole 250 therein is formed in a step in order to connect the latching device insertion hole 120 with the latching pin insertion hole 160, and it moves upward/downward while slidingly contacting a low cam 611, a latching device 400 that is inserted in the latching pin movement hole 250 of the inner body 200, the latching device insertion hole 120 of the outer body 100, and the latching pin insertion hole 160, and moves from side to side therein such that the movement of the outer body 100 is selectively subject to the movement of the inner body 200, a plate 430 that is located at a side of the latching device 400 and prevents oil from discharging from the outer body 100, and an upper seat 300 that partially covers the inner body 200 and an oil inlet 350 and an oil passage 370 are formed on the exterior circumference thereof, wherein the oil passage 370 is connected with the oil inlet 350 and provides the latching device insertion hole 120 with oil, and a lost motion spring 500 that is located in the upper seat 300, covers the inner body 200, and provides the outer body 100 with elastic force.

Further, the oil passage 370 formed in the upper seat 300 is connected with the latching device insertion hole 120 formed in the outer body 100, and is engaged with the outer body 100 in an oil-tight fashion. In addition, the upper seat 300 and the outer body 100 can be integrally and/or monolithically formed if there is no problem in processing of the oil passage 370.

The inner body 200, the outer body 100, and the latching pin 420 are all formed in steps. Hereinafter, the stepped shapes of the inner body will be called a first stepped jaw 211, a second stepped jaw 212, and a third stepped jaw 213, respectively, the stepped shapes of the outer body 100 will be called a first stepped portion 111 and a second stepped portion 112, respectively, and the stepped shapes of the latching pin 420 will be called a first protruded portion 421, a second protruded portion 422, and a third protruded portion 423 respectively.

FIG. 3A is a perspective view of the outer body combined with the upper seat in a bottom plan direction, and FIG. 3B is a bottom plan view of the outer body combined with the upper seat. As shown in FIG. 3, the outer body 100 and the upper seat 300 can be integrally formed while maintaining air-tightness.

The combination may be performed by laser welding.

To combine the outer body 100 with the upper seat 300, an upper circle 550 and a lower circle 551 at which the outer body 100 contacts the upper seat 300 is integrally formed by laser welding such that the oil-tight seal for the operation oil is maintained.

The latching device 400 includes a plunger 410, a latching pin 420, and a latching spring 440. The plunger 410 can be moved from side to side in order to change the valve lift by selective oil supply, and the latching pin 420 contacts the plunger 410 at a side and contacts the stepped jaws 211, 212, and 213 or the stepped portions 111 and 112 such that the movement of the latching pin 420 is restricted by the stepped jaws 211, 212, and 213 or the stepped portions 11 1 and 112.

A protrusion 450 is formed at a side of the plunger such that the oil can be smoothly supplied.

Also, the latching spring 440 covers the latching pin 420, and is located between a contact portion 425 of the latching pin 420 and a supporting portion 125 of the inner body 200 such that the latching pin 420 can be provided with elastic force.

The latching pin 420 according to various embodiments of the present invention, as shown in FIG. 1, is formed with two steps. The diameter D2 of the other side in the latching pin 420 contacting the first stepped portion 111 of the outer body 100 is larger than the inner diameter D1 of the first stepped portion 111 formed in the outer body 100 such that the movement of the latching pin 420 can be restricted by the first stepped portion 111.

In various embodiments of the present invention, as shown in FIG. 2, the latching pin 420 is formed with three steps, and the third stepped jaw 213 has an inner diameter D1 that is smaller than the diameter D2 of the second protruded portion 422 of the latching pin 420 and is formed at the inner body 200 such that the third protruded portion 423 of the latching pin 420 can be inserted in the latching pin insertion hole 160, but the movement of the second protruded portion 422 is restricted by the third stepped jaw 213 of the inner body 200.

The variable valve lift apparatus presses a valve, and this can be performed by a shim 520 formed at the bottom of the inner body 200, while the lost motion spring 500 can be supported by a support 540.

FIG. 5 (A) is a perspective view of a variable valve lift apparatus according to various embodiments of the present invention, FIG. 5 (B) is a perspective view of the variable valve lift apparatus without an outer body, and FIG. 6 is a cross-sectional view of a variable valve lift apparatus according to various embodiments of the present invention.

A variable valve lift apparatus according to various embodiments of the present invention includes an outer body 700 in which oil chambers 960 and 961 are horizontally formed, and protruded portion 720 and 721 are formed inward contacting with an inner body 800 and move upward/downward while contacting the high cam 610, the inner body 800 that is inserted in the center of the outer body 700 in a length direction, and in which a latching pin hole 805 is formed such that it is connected with the oil chambers 960 and 961 of the outer body 700, and moves upward/downward while slidingly contacting the low cam 611 formed at a camshaft 600, first and second latching devices 900 and 901 that move through the latching pin hole 805 of the inner body 800 and the oil chambers 960 and 961 of the outer body 700 and cause the movement of the outer body 700 to be selective with regard to the movement of the inner body 800 because of stepped jaws 920 and 921 of latching pins 910 and 911 that are restricted by protruded portions 720 and 721, plates 930 and 931 that are located at sides of the latching devices 900 and 901 such that discharge of the oil from the outer body 700 is prevented, an upper seat 810 that partially covers the inner body 800 and an oil passage 870 formed therein such that the oil can be supplied into the oil chambers 960 and 961, and a lost motion spring 500 that is located in the upper seat 810 and can provide the outer body 700 with elastic force.

The latching devices 900 and 901 include the latching pins 910 and 911, which are located at the oil chambers 960 and 961 of the outer body 700 and at both sides of the inner body 800, and a side thereof contacts the oil and the other side thereof moves into the latching pin hole 805 of the inner body 800 by selective oil supply to the oil chambers 960 and 961, and latching springs 940 and 941 that cover the latching pins 910 and 911 partially and provide the latching pins 910 and 911 with elastic force.

The latching springs 940 and 941 are formed between the protruded portions 720 and 721 formed in steps on the outer body 700 and the stepped jaws 920 and 921 of the latching pins 910 and 911.

Protrusions 950 and 951 are formed on the latching pins 910 and 911 to protrude outward and the oil chambers 960 and 961 are formed such that the oil is smoothly supplied, and the other sides of the latching pins 910 and 911 are the same size as the inner diameter of the latching pin hole 805 of the inner body 800.

Further, an oil inlet 850 is formed on a side of the upper seat 810, and the oil flowing in through the oil inlet 850 can move through the oil passage 870 formed on the exterior circumference.

The oil passage 870 is formed by engaging the outer body 700 with the upper seat 810 in an oil-tight fashion. If there is no problem in processing of the oil route, as shown in FIG. 3, the upper seat 810 can be integrally formed like above described exemplary embodiments of the present invention.

Operation oil can always be supplied by the oil inlet 850 in an oil-tight fashion while the variable valve lift apparatus is in a high lift mode.

As stated above, after the supplied oil passes the upper seat 810, it is transmitted to the latching pins 910 and 911 through the oil chambers 960 and 961 of the outer body 700.

The discharge of the oil is performed in reverse order. FIG. 3 shows the combination of the upper seat 300 (810) and the outer body 100 (700) according to various embodiments of the present invention, wherein (A) of FIG. 3 is a perspective view of the upper seat 300 (810) and the outer body 100 (700) in a bottom plan view, and (B) of FIG. 3 is a bottom plan view of the upper seat 300 integrally formed with the outer body 100.

To integrally combine the outer body 100 (700) and the upper seat 300 (810) in various embodiments of the present invention, the circles at which the outer body 100 (700) contacts the upper seat 300 (810), i.e., the upper circle 550 and the lower circle 551, may be integrally formed by laser welding, so the operation oil can be sealed in.

Hereinafter, the operation process according to various embodiments of the present invention will be described. First, looking at a low lift mode, FIG. 1A is a cross-sectional view of a variable valve lift apparatus in a low lift mode according to various embodiments of the present invention, and FIG. 4A is a cross-sectional view of a variable valve lift apparatus combined with a cam in a low lift mode according to the various embodiments of the present invention.

As shown in FIG. 1A, supply of oil 151 is stopped in the low lift mode and the remaining oil 151 is discharged outside.

At this time, the discharged path is opposite to the supply path, that is, the oil is stored in the latching device insertion hole 120, and then the oil having passed through the oil passage 370 is discharged through the oil inlet 350.

The latching spring 440 covers the latching pin 420 and is located between the first stepped jaw 211 and the second protruded portion 422 of the latching pin 420, and is supported by a supporting portion 125 of the inner body 200 and contacts a contact portion 425 of the latching pin 420 such that the latching pin 420 can always be provided with elastic force.

Because the latching pin 420 is not inserted in the latching pin insertion hole 160 of the outer body 100 in the low lift mode, the outer body 100 and the inner body 200 can independently move upward/downward by sliding-contact of the high cam 610 and the low cam 611.

Therefore, in this case, as shown in FIG. 4A, the outer body 100 just performs a lost motion by the lost motion spring 500 without contributing to valve lift, such that only the inner body 200 can contribute to the valve lift.

At this time, the shim 520 is formed inside the inner body 200, and a valve 670 moves downward while contacting the shim 520.

Finally, the valve 670 moves downward as much as a lobe of the low cam 611.

On the contrary, oil, as shown FIG. 1B, is supplied in the latching device insertion hole 120 in the high lift mode.

The oil 151 is supplied through the oil inlet 350 formed at the exterior circumference of the upper seat 300, and flows into the latching device insertion hole 120 through the slanted oil passage 370.

A protrusion 450 is formed on a side of the plunger 410 such that the oil can be smoothly supplied in various embodiments of the present invention.

That is, the oil can smoothly flow in by the hollow space obtained by the protrusion 450.

The inflow oil 151 forms hydraulic pressure, and the plunger 410 can be pushed by the hydraulic pressure and the plunger 410 pushes the latching pin 420 so that the latching pin 420 can move.

A diameter D2 of the second protruded portion 422 of the latching pin 420 is larger than the inner diameter D1 of the second stepped portion 112 of the outer body 100 such that the latching pin 420 is restricted by the second stepped portion 112 of the outer body 100.

In other words, the movement of the latching pin 420 can be restricted by the stepped structure without additional devices.

As stated above, the latching pin 420 is partially inserted in the latching pin insertion hole 160 such that the movement of the outer body 100 is subject to the movement of the inner body 200. Further, the inner body 200 contacting the low cam 611 moves downward together with the outer body 100 and no longer contacts the low cam 611 at some stage, but because the movement of the inner body 200 is dependent on the upward/downward movement of the outer body 100 slidingly contacting the high cam 610, the inner body 200 moves further down.

Therefore, as shown in FIG. 4B, the outer body 100 and the inner body 200 move further down, and the high lift mode is fulfilled by the shim 520 connected with the valve 670.

Hereinafter, the operation process according to other embodiments of the present invention will be described.

Various embodiments use the same path of oil 151 and operation principle as with the above-described embodiments, but they differ somewhat in the stepped structure of the latching pin 420, the inner body 200, and the outer body 100.

The latching pin 420, the inner body 200, and the outer body 100 are all formed with two steps such that the latching pin 420 can be restricted by the stepped structure in various embodiments of the present invention, and on the other hand, the latching pin 420 and the inner body 200 are formed with three steps in other embodiments of the present invention.

That is, the first protruded portion 421 of the latching pin 420 contacts the first stepped jaw 211 of the inner body 200, the second protruded portion 422 of the latching pin 420 contacts the second stepped jaw 212 of the inner body 100, and the third protruded portion 423 of the latching pin 420 contacts the third stepped jaw 213 of the inner body 200.

Also, the inner diameter Di of the third stepped jaw 213 is formed with the same size as the inner diameter D1 of the latching pin insertion hole 160 such that the third protruded portion 423 of the latching pin 420 can be inserted into the latching pin insertion hole 160.

By the above structure, in various embodiments of the present invention, the oil, as shown in FIG. 2A, is not supplied in the low lift mode. The inner body 200 and the outer body 100 move upward/downward independently because they are supported by the latching spring 440 that covers the latching pin 420 and is supported by the supporting portion 125 of the inner body 200, and contacts the contact portion 425 of the latching pin 420, such that the latching pin 420 can always be provided with elastic force (referring to FIG. 4A).

On the contrary, in the high lift mode according to various embodiments of the present invention, the oil is supplied through the same path as in the above-described embodiments of the present invention and the latching pin 420 is pushed by a plunger because of hydraulic pressure formed by the supplied oil, and the inner diameter D2 of the second protruded portion 422 is larger than the inner diameter D1 of the third stepped jaw 213 of the inner body 200 such that the latching pin is blocked thereby.

That is, the latching pin 420 can be moved by the plunger 410, but the latching pin 420 is restricted by the third stepped jaw 213 of the inner body 200, so that the upward/downward movement of the inner body 200 is dependent on the upward/downward movement of the outer body 100.

Therefore, the inner body 200 moves downward while contacting the low cam 611, and the inner body 200 moves further down while contacting the low cam 611 at some stage and being subject to the movement of the outer body 100, and in this way, the high lift mode is fulfilled.

At this time, the valve 670 is lifted as much as a lobe of the high cam 610 (referring to FIG. 4B).

Hereinafter, the operation process according to other embodiments of the present invention will be described.

First, the operation process in the low lift mode will be described.

FIG. 6 (A) is a cross-sectional view of a variable valve lift apparatus in the low lift mode according to various embodiments of the present invention, and FIG. 7 (A) is a cross-sectional view of a variable valve lift apparatus combined with a cam in the low lift mode according to such embodiments of the present invention.

Oil is not supplied in the low lift mode.

In this situation, the supplied oil is discharged through the oil passage 870 and the oil inlet 850.

Because the hydraulic pressure is not formed by the oil, only elastic force formed by the latching springs 940 and 941 is exerted on the first and second latching pins 910 and 911, so that the first and second latching pins 910 and 911 are located only at the oil chambers 960 and 961 of the outer body 700 and do not move into the latching pin hole 805 of the inner body 800.

The outer body 700 and the inner body 800 press independently, respectively slidingly contacting the high cam 610 and the low cam 611.

The outer body 700 and the inner body 800 move upward/downward independently, but the outer body 700 performs a lost motion by the lost motion spring 500 without contributing to the valve lift such that the low lift mode is fulfilled.

The valve 670 moves downward as much as a lobe of the low cam 611 contacting the shim 520 located inside the inner body 800.

Hereinafter, the high lift mode according to various embodiments of the present invention will be described. FIG. 6 (B) is a cross-sectional view of a variable valve lift apparatus in the high lift mode according to such embodiments of the present invention, and FIG. 7 (B) is a cross-sectional view of a variable valve lift apparatus contacted a cam in the high lift mode according to such embodiments of the present invention.

Oil is supplied in the high lift mode.

The oil having flowed in through the oil inlet 850 of the upper seat 810 moves into the oil passage 870 and the oil chambers 960 and 961 of the outer body 700.

The oil in the oil chambers 960 and 961 is held oil-tight by the plates 930 and 931, so that the oil is not discharged. The supplied oil forms hydraulic pressure, and pushes the first and second latching pins 910 and 911 so that the first and second latching pins 910 and 911 are moved into the latching pin hole 805 of the inner body 800.

The first and second latching pins 910 and 911 cause the movement of the outer body 700 to be subject to the movement of the inner body 800.

Therefore, when the high cam 610 and the low cam 611 respectively slidingly contact the outer body 700 and the inner body 800, as shown in FIG. 6 (B), the outer body 700 and the inner body 800 move upward/downward together by the high cam 610.

That is, the inner body moves down as much as a lobe of the high cam 610, and as the shim 520 located in the inner body 800 moves downward, the valve 670 contacting the shim 520 moves downward with it. Therefore, the valve lift is increased.

For convenience in explanation and accurate definition in the appended claims, the terms upper or lower, inside or outside, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. A variable valve lift apparatus comprising: an outer body including a horizontally extending hole, and that moves upward/downward while slidingly contacting a high cam; an inner body inserted in the outer body, a hole is formed therein in steps such that the hole of the inner body is connected with the hole of the outer body, and moves upward/downward while slidingly contacting a low cam; a latching device inserted in the holes of the outer body and the inner body, and causes the movement of the outer body to be selectively dependent on the movement of the inner body; a plate located at a side of the latching device such that oil discharge from the outer body can be prevented; an upper seat that partially covers the inner body, and includes an oil passage; and a lost motion spring located in the upper seat and providing the outer body with elastic force.
 2. A variable valve lift apparatus of claim 1, wherein the latching device comprises a plunger that moves from side to side by selective oil supply, a latching pin of which one side thereof contacts the plunger and an other side thereof is formed in steps such that the latching pin is blocked by the stepped holes of the outer body and the inner body, and a latching spring that covers the latching pin and provides the latching pin with elastic force while being supported by the supporting portion of the outer body.
 3. A variable valve lift apparatus of claim 2, wherein the latching pin is formed with two steps, and the inner diameter of the outer body is smaller than the diameter of the end in the other side of the latching pin such that a stepped jaw is formed to prevent the latching pin from moving.
 4. A variable valve lift apparatus of claim 2, wherein the latching pin is formed with three steps, and the inner diameter of the inner body is smaller than the diameter of the second protruded portion in the latching pin at which a stepped portion is formed to prevent the latching pin from moving.
 5. A variable valve lift apparatus of claim 2, wherein a protrusion is formed at a side of the plunger.
 6. A variable valve lift apparatus of claim 1, wherein the oil passage formed in the upper seat is inclined, and is connected with a latching device insertion hole formed in the outer body.
 7. A variable valve lift apparatus of claim 2, wherein the oil passage formed in the upper seat is slanted, and is connected with a latching device insertion hole formed in the outer body.
 8. A variable valve lift apparatus of claim 7, wherein a shim contacting a valve is disposed at the bottom of the inner body.
 9. A variable valve lift apparatus comprising: an outer body including a horizontally extending oil chamber and a protruded portion formed inward and moves upward/downward while slidingly contacting a cam; an inner body inserted in the outer body, a latching pin hole is formed to be connected with the oil chamber of the outer body, and moves upward/downward while slidingly contacting a low cam; at least one latching device that moves through the latching pin hole and the oil chamber and causes the movement of the outer body to be selectively dependent on the movement of the inner body; a plate located at a side of the latching device such that discharge of the oil from the outer body is prevented; an upper seat that partially covers the inner body and in which an oil passage is formed; and a lost motion spring located in the upper seat, and provides the outer body with elastic force.
 10. A variable valve lift apparatus of claim 9, wherein the latching device is comprised of a latching pin of which a side thereof contacts oil and an other side thereof moves into the inner body by selective oil supply, and a latching spring that partially covers the latching pin and provides the latching pin with elastic force.
 11. A variable valve lift apparatus of claim 10, wherein the latching device is respectively located at both ends of the latching pin hole of the inner body.
 12. A variable valve lift apparatus of claim 10, wherein an inner diameter of the other side in the latching pin is the same size as the diameter of the latching pin hole of the inner body.
 13. A variable valve lift apparatus of claim 10, wherein the latching spring is located between the protruded portion of the outer body formed in a step, and the jaw of the latching pin.
 14. A variable valve lift apparatus of claim 10, wherein a protrusion is formed at a side of the latching pin.
 15. A variable valve lift apparatus of claim 9, wherein the oil passage formed in the upper seat is connected with an oil chamber formed in the outer body.
 16. A variable valve lift apparatus of claim 10, wherein the oil passage formed in the upper seat is connected with an oil chamber formed in the outer body.
 17. A variable valve lift apparatus of claim 16, wherein the outer body and the upper seat are integrally formed.
 18. A variable valve lift apparatus of claim 1, wherein the outer body and the upper seat are integrally formed.
 19. A variable valve lift apparatus of claim 16, wherein the outer body and the upper seat are integrally formed. 